The astable multivibrator can be used as a clock pulse generator for digital ICs like counters. CD 4017 is a decade counter, so ten events can be run in sequence with this IC. Clock pulse can be applied to the astable multivibrator with constant or variable frequency option as required.
Sequential Runner Using 555-Timer
The duration of the desired stage can be increased in steps by using diodes as shown in circuit diagram. This is generally used for running lights. By using variable frequency circuit, the speed of running effect can be varied. A number of stages can be varied by connecting the next stage of desired last stage to the MR (Master Reset) pin.